Method of Detecting and Correcting Focus Drift of Variable Focus Lens for Fixed Focus Applications

2. The method of claim 1, wherein the near focal plane distance is equal to or greater than a minimum focal plane threshold.

3. The method of claim 2, wherein the minimum focal plane threshold is at a predetermined distance smaller than the central focal plane distance.

4. The method of claim 1, wherein the far focal plane distance is equal to or less than a maximum focal plane threshold.

5. The method of claim 2, wherein the maximum focal plane threshold is at a predetermined distance greater than the central focal plane distance.

6. The method of claim 1, wherein the reference metric is stored in a memory of the imaging system.

8. The method of claim 1, wherein the first image property value includes one or more of an image contrast, resolution, sharpness, edge detection, or modulation transfer function.

9. The method of claim 1, wherein the second image property value includes one or more of an image contrast, resolution, sharpness, edge detection, or modulation transfer function.

10. The method of claim 1, wherein determining the image quality metric comprises determining one of a difference between the first and second image property values, an addition of the first and second image property values, a quotient of the first and second image property values, or an average of the first and second image property values.

11. The method of claim 1, wherein the central focal plane distance is half way between the near focal plane distance and the far focal plane distance.

12. The method of claim 1, wherein adjusting the central focal plane distance of the variable focus lens comprises adjusting a voltage applied to the variable focus lens.

13. The method of claim 1, wherein adjusting the central focal plane of the variable focus lens comprises adjusting a position of an optical element of the imaging system.

14. The method of claim 1, wherein the variable focus lens comprises a liquid lens.

15. The method of claim 1, wherein the first object of interest and second object of interest are a same object of interest.

16. The method of claim 1, wherein the threshold of the reference metric is a threshold relative to the near plane focal distance.

17. The method of claim 1, wherein the threshold of the threshold of the reference metric is a threshold relative to the far plane focal distance.

18. The method of claim 1, wherein the threshold of the threshold of the reference metric is a threshold relative to the central plane focal distance.